Headstream Technologies Interview Questions and Answers

Garbage collection is an automatic memory management process that frees up memory occupied by objects that are no longer in use.

• Garbage collection is a process of identifying and freeing up memory that is no longer in use by the program.

• It is done automatically by the programming language runtime environment.

• Garbage collection helps prevent memory leaks and improves program performance.

• Examples of programming languages...read more

SOLID is a set of principles for object-oriented programming to make software more maintainable, scalable, and robust.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open-Closed Principle: A class should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Subtypes should be substitutable for their base types.

• I - Interface Segregation Principle: A c...read more

CLR stands for Common Language Runtime. It is a component of .NET framework that manages execution of .NET programs.

• CLR is responsible for memory management, security, and exception handling.

• It compiles the intermediate language code into machine code.

• CLR provides a common type system and runtime environment for all .NET languages.

• It allows for cross-language integration and interoperability.

• Examples of languages that ...read more

Abstract classes provide a blueprint for other classes to follow and cannot be instantiated.

• Abstract classes are used when we want to provide a common interface for a group of related classes.

• They cannot be instantiated and must be extended by a subclass.

• Abstract methods are declared in the abstract class and implemented in the subclass.

• They can have both abstract and non-abstract methods.

• Example: Animal is an abstract...read more

Association, Composition and Aggregation are three types of relationships between classes in object-oriented programming.

• Association is a relationship between two classes where one class uses the other class as a parameter or return type.

• Composition is a relationship between two classes where one class owns the other class and is responsible for its creation and destruction.

• Aggregation is a relationship between two cla...read more

Identifying slow running query in a 1000 line stored procedure

• Use SQL Server Profiler to trace the stored procedure and identify the slow running query

• Check the execution plan of the stored procedure to identify the slow running query

• Use SET STATISTICS TIME ON to measure the execution time of each query in the stored procedure

• Divide the stored procedure into smaller parts and test each part to identify the slow running...read more

Clustered index is only one for a table to ensure efficient data retrieval and storage.

• Clustered index determines the physical order of data in a table.

• Only one clustered index can be created per table.

• It is recommended to choose a column with unique and sequential values as the clustered index.

• Clustered index is used for range searches and sorting.

• Non-clustered indexes can be created for additional search paths.

Temporary table is a table that exists temporarily in the database and is used to store intermediate results.

• Temporary tables are created and used within a single session or transaction.

• They are stored in the tempdb database in SQL Server.

• They can be used to store intermediate results during complex queries or to simplify complex joins.

• They are automatically dropped when the session or transaction ends or when they are...read more

SQL covered index is an index that contains all the columns needed for a query, reducing the need for table lookups.

• A covered index can improve query performance by reducing the number of disk I/O operations.

• It is created by including all the columns needed for a query in the index.

• Covered indexes are particularly useful for queries that involve large tables or complex joins.

• Example: CREATE INDEX idx_name ON table_name...read more

Table variable is a variable that holds a table-like structure in memory for temporary use.

• Table variables are declared using the DECLARE keyword in SQL Server.

• They can be used to store temporary data within a stored procedure or a batch of SQL statements.

• Table variables have a scope limited to the batch or stored procedure in which they are declared.

• They are automatically dropped when the batch or stored procedure com...read more

Optimizing query to fetch records from employee table based on city

• Create an index on the City column

• Use a WHERE clause with an index hint

• Use a stored procedure to cache the query results

• Use a materialized view to precompute the query results

Yes, we can create an index for a varchar column to improve query performance.

• Indexes can be created on varchar columns to speed up searches.

• Example: CREATE INDEX idx_name ON table_name (varchar_column);

• Consider the length of the varchar; longer lengths may impact performance.

• Partial indexes can be created for large varchar columns: CREATE INDEX idx_name ON table_name (varchar_column(10));

• Using indexes on varchar colum...read more

MSDB is a system database in SQL Server used for managing SQL Server Agent jobs, alerts, and operators.

• MSDB stands for Microsoft SQL Server Database

• It stores metadata and configuration information for SQL Server Agent

• It contains tables for job scheduling, alerts, and operators

• It also stores backup and restore history information

SQL NOLOCK is a query hint used to allow a SELECT statement to read data from a table without acquiring a shared lock.

• NOLOCK is used to improve query performance by allowing dirty reads

• It is not recommended to use NOLOCK in production environments

• Other query hints include UPDLOCK, ROWLOCK, and XLOCK

Async and Await are keywords used in asynchronous programming in JavaScript.

• Async and Await are used to handle asynchronous operations in JavaScript.

• Async is used to define a function that returns a promise.

• Await is used to wait for the promise to resolve before continuing the execution.

• Async and Await make asynchronous code look like synchronous code.

• Async and Await are supported in modern browsers and Node.js.

Collections are generic classes to store and manipulate groups of objects. Dictionary is a collection of key-value pairs. KeyValuePair is a struct that represents a key-value pair.

• Collections are used to store and manipulate groups of objects.

• Dictionary is a collection of key-value pairs where each key is unique.

• KeyValuePair is a struct that represents a key-value pair and is used in Dictionary.

• Collections and Dictiona...read more

Yes, SQL Functions can be used on the JOIN Clause.

• SQL Functions can be used on the JOIN Clause to manipulate the data before joining.

• Examples of SQL Functions that can be used on the JOIN Clause are CONCAT, SUBSTRING, and DATE_FORMAT.

• Using SQL Functions on the JOIN Clause can improve query performance and reduce the amount of data transferred.

SQL functions return a single value of a specified data type.

• SQL functions can return various data types such as integer, string, date, etc.

• The return type of a function is specified in the function declaration.

• Functions can be used in SELECT, WHERE, and other SQL statements to manipulate data.

• Examples of SQL functions include COUNT, AVG, MAX, MIN, and CONCAT.

• Functions can also be user-defined using the CREATE FUNCTION...read more

MVC Data Annotations are attributes used to define validation rules and metadata for model properties in ASP.NET MVC applications.

• Used to validate user input on the server-side

• Can be used to specify display names, format strings, and more

• Examples include [Required], [StringLength], and [RegularExpression]

Partial views are reusable components of a view that can be rendered within other views.

• Partial views are used to break down complex views into smaller, more manageable pieces.

• They can be used to display common elements across multiple views, such as headers or footers.

• Partial views can be rendered within other views using the @Html.Partial() method in ASP.NET MVC.

• They can also be passed data from the parent view using...read more

Data can be transferred between controllers using various methods such as delegation, notifications, or segues.

• Delegation pattern can be used to transfer data between controllers

• Notifications can be used to broadcast data to multiple controllers

• Segues can be used to pass data between controllers during a transition

• Data can also be stored in a shared data model or database for access by multiple controllers